1. Field of the Invention
The present invention relates to antennas for satellites. More particularly, the present invention relates to an antenna system that includes a positioning mechanism for a reflector.
2. Discussion of Related Art
Communications satellites in a geosynchronous orbit may utilize antennas for uplink and downlink communications with the Earth. A satellite uplink communications signal is transmitted to a satellite from one or more ground stations located on the Earth; and a satellite downlink communications signal is transmitted from a satellite to one or more ground stations located on the Earth. The uplink and downlink signals are received and transmitted respectively at particular frequency bands that are typically in the ratio of about 3:2 (uplink frequency band: downlink frequency band) for Ka band. The signals may also be coded.
A satellite is equipped with antennas or antenna systems to receive and transmit the uplink and downlink signals, respectively. To minimize the number of satellites in a constellation and maximize communications capabilities, it is desirable for each satellite to have the capability to communicate with locations on the Earth within the satellite""s field of view.
Embodiments of the present invention may provide an antenna system for a satellite. The antenna system may include a main reflector, a subreflector, an antenna boom, and a positioning mechanism. The antenna boom may include a first boom component to support the main reflector and a second antenna boom component to support the subreflector. The first boom component may include a first main support, a fitting and a second main support. The fitting may couple the first main support to the second main support. The positioning mechanism may be provided within the fitting (e.g. within an inner area) to support the main reflector. The positioning mechanism may be capable of adjusting a position of the main reflector.
The positioning mechanism may be a wobble plate, a compact small angle positioner (CSAP), a biaxial gimbal, for example. Other types of positioning mechanisms are also possible.
The first main support and the second main support may each be a tubular graphite support. The fitting may be a metal fitting, such as an aluminum or titanium fitting, or may be a graphite fitting. The fitting may be bonded and/or bolted to the first graphite support and may be bonded and/or bolted to the second graphite support. The positioning mechanism may also be bonded/bolted to the fitting.
Embodiments of the present invention may also include an antenna system that includes an antenna boom having a first boom part, a second boom part, a third boom part, and a mechanism to support and adjust a position of a reflector such as the main reflector. The mechanism may be coupled to a location within an inner area of the second boom part.